Biomass Processing

ABSTRACT

Processing systems and methods are described for pre-processing processing of biomass. The systems include an extruder characterized by one or more ports though which acids and/or bases may be introduced to the biomass during extrusion. The acids may be selected to hydrolyze the biomass and the base may be selected to neutralize the acid. Neutralization can occur using a solid base within the extruder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority and benefit to U.S. provisional patentapplication Ser. No. 63/053,099 filed Jul. 17, 2021. The disclosure ofwhich is hereby incorporated herein by reference.

BACKGROUND Field of the invention

The invention is in the field of biomass processing.

Related Art

Mixed biomass present in residential and agricultural waste presents aprocessing challenge in that the mechanical properties of the bulkmaterial can vary widely. In order to realize value added products fromthis material it is preferably pre-processed into a uniform materialsuitable for chemical attack. Optimal depolymerization of cellulose andhemicellulose to their respective monomers occurs when the feedstock hasa small particle size a low degree of crystallinity.

Conversion of lignocellulosic biomass to value-added products at anindustrial scale requires an initial size reduction step(preprocessing). Two technologies are typically used for this step:cutting mills and hammer mills. Cutting mills work well for fibrous andsoft materials, but not so well for hard materials such as grains.Hammer mills optimally process these hard materials. Both of thesetechnologies may be optimized for size reduction. Although sizereduction is needed for further processing, extended pre-processingtimes will reduce plant profitability and therefore should be keptshort. Size reduction power requirements can vary from 4-400 kWh/MT. Themost common form of biomass structure disruption is steam explosionwhere the feedstock is subjected to steam under pressures of 1-3 MPa andtemperatures of 180-240° C. This is energy intensive.

SUMMARY

Systems and methods of (pre-) processing biomass for size reductionand/or preparation as feedstock for further conversion are presented.These include mechanical and/or chemical processing to break down thebulk structure of biomass. In various embodiments, the systems andmethods are configured to optimize size reduction, fiber disruption,and/or amorphization. Ideally, a uniform easily conveyed material isproduced using the systems and methods described herein. Suchpre-processed biomass can produce consistent ultimate yields of fuels orchemicals produced from biomaterials, e.g., plants. To meet this goal acombined mechanical and chemical approach is used. Specifically, thisapproach may include simultaneous mechanical processing and the use ofacids to break down biomass. Optionally, acids are neutralized using abase within the mechanical processing system.

Natural cellulose is highly crystalline, which severely limits its acidand enzymatic hydrolysis rate. The crystallinity of cellulose can bereduced through mechanical processing and/or chemical methods. Chemicalhydrolysis can eventually reduce the crystallinity of the feedstock.However, extended contact with strong acids leads to degradation oflignin in the biomass and lowers the feedstock's value. Acid processingshould, thus, preferably occur over a limited time period, and beterminated after this limited time period.

In some embodiments, mechanical processing through steam explosion ormechanical milling is used to sufficiently reduce the crystallinity ofthe parent material to realize improved hydrolysis rates while at thesame time limiting the amount of undesirable by-products. Thecompressive events in mechanical processing can alternatively berealized in a screw extruder through the use of multi-lobe mixingelements. The shape and location of these elements allow control ofamorphitization and hydrolysis rates and subsequently the end productsmechanical and chemical properties. Proper application of mixing,hydrolysis, and neutralization can result in a product with a freemoisture content below 20% or 10% and a bulk modulus less than 66% or75% of the unprocessed feedstock. As the biomass material passes betweentwo mixing lobes it experiences high compressive force. It also can becompressed against the barrel of the extruder through the use of taperedscrews. Both processes will reduce the crystallinity of theholocellulose present in the feedstock.

In some embodiments, the time during which the biomass is exposed to theacid(s) is controlled by the addition of one or more base such as, forexample, slaked lime (Ca(OH)2) or lime (CaCO3). The addition of the baseis optionally achieved via a (second) port in the extruder. As such, theaddition of acids and/or bases may be performed “in-line” while thebiomass is within a flow-through processing system including one or moreextruders. In some embodiments the biomass is processed using more thanone extruder in series, wherein the output of a first extruder is passedto the input of second extruder. Input ports may be disposed within orbetween sections of an extruder.

Since the material is flowing through the extruder, the addition of abase can occur downstream from the addition of the acid. The positionsat which the acid and base are added and the flow rate within theprocessing system can be used to control the time during which thebiomass is exposed to the acid (acidic conditions). This allows forsufficient time for amorphitization of the biomass while controlling thedegradation of lignin by the acid. The addition of the base enhances thedisruption of the biomass and neutralizes the acid(s). The(pre-processed) biomass flowing out of the extruder is ready forenzymatic hydrolysis and holocellulose removal. This enhanced approachmakes the process feedstock agnostic to the expected variations in thephysical properties of the unprocessed biomass, while taking advantageof the relatively high quality achievable using extruder pre-processedbiomass. Additionally, a minimum of acid may be consumed and no acidicproducts may be produced. The output of the flow-through processingsystem is acid processed but is neutralized before leaving theflow-through processing system. This eliminates the need for tankneutralization and subsequent waste disposal. In some embodiments,carbon dioxide gas is also directed through the screw extruder tosuppress oxidation reactions that can occur during preprocessing ofbiomass and reduce lignin quality. Carbon dioxide is optionally added tothe extruder as a gas, liquid, solid or supercritical fluid.

Various embodiments of the invention include a flow-through biomassprocessing system comprising: a screw extruder configured to conveybiomass through the processing system such that processed biomasscontinuously exits the flow-through biomass processing system, the screwextruder including: a housing, at least a first shaft including asection configured to convey the biomass through the screw extruder anda section configured to compress the biomass, and a first portconfigured to introduce a base to the biomass within the screw extruder;and a motor configured to rotate at least the first shaft. Optionally,the screw extruder is a multi-screw extruder and includes at least asecond shaft, and including a section configured to convey the biomassthrough the first screw extruder and a section configured to compressthe biomass. Optionally, the processing system further comprises asecond port configured to introduce an acid to the biomass within thescrew extruder, wherein the second port is disposed upstream of thefirst port, relative to the flow of the biomass through the screwextruder, the acid being configured to neutralize the base.

Various embodiments of the invention include a method of processingbiomass, the method comprising: introducing the biomass to a screwextruder, the screw extruder including a first shaft having a sectionconfigured to convey the biomass through the screw extruder andoptionally having a second shaft configured to compress the biomass butnot necessarily convey the biomass through the screw extruder;introducing an acid to the biomass, the acid configured to hydrolyze thebiomass; introducing a base to the biomass within the screw extruder,the base being configured to neutralize the acid introduced to thebiomass, the acid being neutralized within the screw extruder; receivinga continuous flow output of the screw extruder, the output including thebiomass neutralized by the base.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating components of a biomassprocessing system according to various embodiments of the invention.

FIG. 2 illustrates method of processing biomass, according to variousembodiments of the invention.

FIG. 3 illustrates a twin screw extruder, according to variousembodiments of the invention.

FIG. 4 illustrates a multi-stage extruder, according to variousembodiments of the invention.

FIG. 5 illustrates mixing lobes, according to various embodiments of theinvention.

DETAILED DESCRIPTION

The microstructure of biomass is preferably disrupted prior to furtherchemical and/or enzymatic processing for maximum holocellulose removal.Plant cell walls are composed of crystalline cellulose fibrils,hemicellulose, and lignin. Feedstocks with high cellulose contentrequire further processing to improved holocellulose removal. However,high shear processing can also disrupt the structure of the feedstock.This is approach may be applied in the production of nanocellulosefibers and/or applied to biomass depolymerization. High shear withcontinuous processing is easily achieved in a co-rotating twin-screwextruder where high shear occurs in modular zones utilizing mixinglobes. In various embodiments, after size reduction, an ideal materialwill have a particle size less than 10, 5 or 3 mm.

FIG. 1 is a block diagram illustrating components of a biomassProcessing System 100 according to various embodiments of the invention.Processing System 100 is a flow-through system including an Extruder100, a Motor 115, optional Control Logic 120, and/or optional (one ormore) Sensors 125. As used herein, a “flow-through” system is one inwhich the material being processed is continuously feed into the systemand processed material continuously exits the system. A flow-throughsystem can be contrasted with a “batch” system in which material isprocessed in discrete batches.

Extruder 110 is a screw extruder configured to convey biomass throughthe processing system such that processed biomass continuously exitsProcessing System 100. Extruder 110 may be a single screw or multi-screw(e.g., dual) extruder. Extruder 100 includes a Housing 130 configured tocontain the biomass within Extruder 110. Housing 130 is typically a hardmaterial such as carbon steal, a steel-iron-nick alloy, stainless steel,tungsten carbide, titanium, Inconel, chromium, and/or other metal.Housing 110 is hollow, being configured to hold the biomass and one ortwo Shafts 135. (Two Shafts 135 for a dual-screw extruder, etc.) Shafts135 are typically made of hard materials such as those discussed hereinregarding Housing 130. Shafts 135 operate by rotation within Housing 130and are rotated using Motor 115.

Shafts 135 optionally include multiple sections (e.g., 1, 2, 3, 4 ormore) configured to serve different functions. For example, somesections may be configured to convey (e.g., drive, move or propel) thebiomass through Extruder 110, while other sections may be configured toapply compressive forces to and mix the biomass. An exemplary embodimentincludes two “convey” sections with a third “compression” sectiondisposed between them. Compression sections may also be referred toherein as “mixing” sections. Other embodiments may include: one conveysection and one compression section, three convey sections interspacedby 2 compression sections, and/or additional sections. In someembodiments a section is configured to both convey and compress/mix thebiomass. Examples of sections that may be included in Shafts 135 arediscussed elsewhere herein. FIG. 1 illustrates a First Section 140 and aSecond Section 145, including Shafts 145. First Section 140 may beupstream from Second Section 145. First Section 140 may be a conveysection while Second Section 145 may be a compression section. Anoptional third section may be configured to further convey the biomassthrough Extruder 110.

Extruder 110 further includes a First Port 150 and/or a Second Port 160.First Port 150 being disposed closer to an input of Extruder 110relative to Second Port 160, the input being where biomass is introducedinto Extruder 110. First Port 150 and Second Port 160 are configured forintroducing reagents from the exterior of Housing 130 to the biomasswithin Extruder 110. First Port 150 and/or Second Port 160 may beconfigured for introducing (to the biomass) liquids, solids, lubricants,surfactant, steam, acids, bases, enzymes, oils, oxidizers, supercriticalfluids, and/or the like. For example, in some embodiments, First Port150 is configured for introducing an acid to the biomass. The acid maybe configured to promote decomposition of the biomass. Likewise, SecondPort 160 may be configured for introducing a base to the biomass, thebase typically being configured to neutralize the acid. Second Port 160is optionally configured to introduce the base as a solid.

In an exemplary embodiment, First Port 150 is disposed near an input toExtruder 110 such that the acid is introduced to the biomass at a pointwhere the acid and biomass will be mixed by the rotation of the Shafts135. In this embodiment, Second Port 160 may be disposed closer to theoutput (downstream from the input) of Extruder 110 such that the acid isneutralized after some time of being in contact with the biomass, andafter the biomass has been mixed and/or exposed to compression in acompression section of Extruder 110. The Second Port 160 is optionallydisposed such that additional mixing occurs before the biomass leavesExtruder 110, giving opportunity for the acid and base neutralizationreaction to occur within Extruder 110. Given sufficient base andopportunity for the acid to react with the base, the processed biomassthat exits Processing System 100 and/or Extruder 110 may be neutralizedusing the base. Second Port 160 is optionally configured to add aquantity of base to the biomass sufficient to neutralize the acid.Second Port 160 may be configured to add the base as a liquid and/orsolid.

First Port 150 is optional in embodiments in which the acid is added tothe biomass prior to introducing the biomass to Extruder 110. Extruder110 may include more than two input ports. First Port 150 and SecondPort 160 are optionally configured to introduce water, CO₂,supercritical water, steam, supercritical CO₂, and/or the like to thebiomass.

Motor 115 may be an electric motor, an internal combustion motor, amicro turbine, and/or the like. Motor 115 optionally includes a system(e.g., gearing, reducer and/or transmission) configured to adjust thetorque applied by Motor 115 to Shafts 135. Motor 115 and/or the torqueadjustment system are optionally controlled by Control Logic 120.

Control Logic 120 is configured to use the output of Sensors 125 tocontrol the operation of Processing System. The “logic” of Control Logic120 includes: hardware, firmware, and/or software stored on anon-transient computer readable medium. Control Logic 120 may furtherinclude a user interface, electrical/signal connections to Sensors 125and/or Motor 115, electrical/signal connections to First Port 150 and/orSecond Port 160, data storage, and/or the like. In some embodiments,Control Logic 120 includes a programmable printed circuit boardincluding electronic circuits configured to perform the functions ofControl Logic 120.

Control Logic 120 is optionally responsive to the outputs of one or moreSensors 125 configured to detect characteristics of the biomass or stateof Processing System 100. For example, in some embodiments, ControlLogic 120 is configured to control Motor 115 so as to adapt therotational rate or torque of Shafts 125 based on detectedcharacteristics of the biomass. In another example, Control Logic 120 isconfigured to deduce characteristics of the biomass based on measurementof the speed(s) of Shaft(s) 135, electrical current provided to Motor115, and/or torque applied by Motor 115 to Shafts 135.

In some embodiments, Control Logic 120 is configured to automaticallydetermine content of the biomass. For example, using Sensors 125,Control Logic 120 may automatically determine a moisture content of thebiomass, a structural profile of the biomass (e.g., how many leaves,wood chips or sludge), a temperature of the biomass, a pH of thebiomass, an age of the biomass (e.g., green leaves or brown),spectroscopic characteristics of the biomass (e.g., wavelength dependentproperties), a gas content of the biomass (e.g., methane content),and/or the like.

Control Logic 120 is optionally configured to determine an amount ofacid or base to add to the biomass based on any of the detectedcharacteristics, and to add the determined amount using First Port 150,Second Port 160, and/or some other port (optionally through Housing130). Such determinations may be made based on any combination of thedetermined biomass characteristics and/or content discussed herein.Optionally, First Port 150 and Second Port 160 include a dispenserconfigured to introduce a controlled amount of liquid and/or solid tothe biomass. Such dispenser is optionally configured to dispensespecific volumes or weights under the control of Control Logic 120. Awide range of suitable dispensers for liquids and/or solids are known inthe art of material handling.

In some embodiments, Control Logic 120 is configured to determine anamount of the base to add to the biomass based on an amount of the acidadded to the biomass. For example, an amount of acid to add to thebiomass may be determined based on the pH, types of materials, and/ormoisture included in the biomass, then after making this determination,Control Logic 120 may determine an amount of base to add to the biomasssuch that the acid is approximately neutralized by the base.

In some embodiments, Control Logic 120 is configured to add a fluidand/or lubricant to the biomass, optionally via First Port 150, SecondPort 160, some other port, and/or prior to introducing the biomass toExtruder 110. The lubricant may be liquid or solid, and is optionallyselected to be acid resistant. In some examples, a solid lubricantincludes water, steam, CO₂, carbon or polymer material that is acidresistant, but that may be decomposed by further processing of thebiomass, e.g., during depolymerization of cellulose or hemicellulose.The amount of fluid and/or lubricant to be added to the biomass may bedetermined by Control Logic 120 based on any of the biomasscharacteristics and/or content discussed herein. For example, the amountmay be based on a detected rotational rate or torque of Shafts 135, adryness of the biomass, and/or contents of the biomass.

Sensors 125 may include any of a large variety of sensors, includingthose configured to detect the biomass characteristics and/or componentsdiscussed herein. Sensors 125 may consist of one or multiple sensors.Examples of Sensors 125 include, but are not limited to: moisturesensors, pH sensors, temperature sensors, cameras (and associated imageprocessing logic), weight sensors, spectroscopic sensors, weightsensors, acoustic sensors, electrical current sensors, mass sensors,lidar, radar, torque sensors, and/or the like. Camera sensors may beused to detect content, age, size distribution, and/or color of thebiomass. These characters may be derived from images using imageprocessing logic.

Sensors 125 may be disposed within any part of Processing System 100.For example, mass and camara sensors may be disposed before the input toExtruder 110, pH and moisture sensors may be disposed proximate to FirstSection 140, a current sensor or torque may be coupled to Motor 115, anda temperature sensor may be disposed at the output of Extruder 110.

FIG. 2 illustrates methods of processing biomass, according to variousembodiments of the invention. These methods are optionally performedusing Processing System 100 as discussed elsewhere herein.

In an Introduce Step 210, biomass is introduced into an extruder, suchas Extruder 110. This may be accomplished, for example, using a funnel,conveyor, screw feeder, and/or the like. Extruder 110 is optionallydisposed horizontally or vertically. The rate (in volume or weight) ofbiomass introduced is optionally controlled by Control Logic 120.

In an optional Analyze Step 220, characteristics and/or content of thebiomass are determined using Sensors 125. Analyze Step 220 can includeuse of any of the Sensors 125 discussed herein to determine any of thebiomass characteristics and/or contents discussed herein. Parts ofAnalyze Step 200 may be preformed prior to Introduce Step 210 or after aReceive Step 260 (discussed further below), or at any point/timetherebetween. For example, moisture and contents may be detected priorto introduction of the biomass to Extruder 110. Temperature may bedetected at various positions with Extruder 110, and pH may be detectedafter the biomass has been extruded from Extruder 110.

In an optional Adapt Step 230, Control Logic 120 is used to adapt theoperation of Processing System 100 based on characteristics and/orcontents (or other information) determined in Analyze Step 220. Suchadaptation can include, for example, changing an amount of biomassintroduced into Processing System 100, changing an amount of acid and/orbase introduced into Processing System 100, changing operation of Motor115, changing a temperature of Extruder 110, adding a lubricant to thebiomass, and/or the like.

In an Add Acid Step 240, an acid is introduced to the biomass,optionally within Extruder 110 and optionally via First Port 150. Theacid is typically configured to hydrolyze the biomass. Add Acid Step 240may occur prior to any of the preceding steps. An amount of acidintroduced is optionally determined using Control Logic 120 as discussedelsewhere herein.

In an optional Add Base Step 250, a based is introduced to the biomass,optionally via Second Port 155. Typically, an amount of base added isapproximately sufficient to neutralize the acid introduced in Add AcidStep 240. An amount of base introduced is optionally determined usingControl Logic 120 discussed elsewhere herein. The base may be added as asolid or a liquid. The base may be added at a location within Extruder110 such that mixing and extrusion of the biomass between theintroduction of the base and the exit of the Extruder 110 is sufficientto approximately neutralize the acid in Add Acid Step 240, withinExtruder 110. Thus, the base and biomass may be mixed in a section ofExtruder 110 downstream from Second Port 155. The acid is typicallyadded upstream from a location within Extruder 110 at which the base isadded. The amount of base added is optionally determined using ControlLogic 120 based on the amount of acid added to the biomass.

In a Receive Step 250, the processed (e.g., hydrolyzed) and optionallyneutralized by the base, biomass is received at an output/exit ofExtruder 110. The biomass is typically received as a continuous flowoutput, in contrast to a batch mode. The biomass may then be furtherprocessed to obtain desirable materials.

FIG. 3 illustrates a twin screw Extruder 110, according to variousembodiments of the invention. Co-rotating twin-screw extruders can beused to efficiently disrupt the fibrous structure of biomass in acontinuous process. In this example a twin Shafts 135 are disposedwithin Housing 130. The Housing 130 includes a First Port 150 and aSecond Port 160 configured for introduction of any of the materials(e.g., acid and base) discussed herein. Shafts 135 are driven by a Motor115.

FIG. 4 illustrates a multi-stage Extruder 110 in cross-section,according to various embodiments of the invention. The illustratedexample of Extruder 110 includes three sections, a First Section 140,Second Section 145, and a Third Section 410. Optionally First Section140 and Third Section 410 are convey sections and Second Section 145 isa compression (mixing) section. Third Section 410 is optionally anembodiment of First Section 140 and/or Second Section 145. FIG. 4 alsoillustrates an Input 420 disposed upstream from an Output 430. TheHousing 130 shown in FIG. 4 includes First Port 150, Second Port 160 andan optional Third Port 440. Third Port 440 is optionally an embodimentof First Port 150 and/or Second Port 155. Alternative embodiments ofExtruder 110 may include additional sections and/or ports. Alternativeembodiments may include 2, 3, 4 or more conveyance regions (sections)separated by compression/mixing regions.

FIG. 5 illustrates mixing Lobes 510, according to various embodiments ofthe invention. Such Lobes 510 may be found in compression (e.g., mixing)sections of Extruder 110. Lobes 510 are attached to and rotated byShafts 135. This rotation produces a high amount of mixing (520) andcompression at Compression Regions 530. In the Compression Regions 530both compressive and shear forces dominate mechanical processing.Brittle materials are easily fragmented under the application ofcompressive force, while soft materials (e.g., fibrous biomass) are moreeasily processed by the application of shear force.

EXEMPLARY EMBODIMENTS

At least 1, 2, 3 or 5 mass percent of a dilute acid (or any rangebetween these values) such as hydrochloric, phosphoric, and/or sulfuricacids are used as the “acid” discussed herein. The acid will partiallyhydrolyze the surface of the fibers and increase its plasticity enablingflow through the extruder. The acid is optionally added to the biomassprior to introduction of the biomass to the extruder. Alternatively, insome embodiments, the acid is added to the extruder though a port in theextruder, e.g., First Port 150.

Various embodiments of Processing System 100 can include any combinationof the following: A twin screw co-rotating screw (Shafts 135) extruderswith a bore greater than 5 cm and a length greater then 1.5, 2 or 3meters. The screw possesses at least 2 mixing regions (e.g., embodimentsof First Section 140 and Second Section 145) each consisting of a set ofmixing Lobes 510 and 3 conveyance regions (e.g., embodiments of FirstSection 140 and Second Section 145) comprising of intermeshedco-rotating screws. An Exit 430 of the extruder, Exit 430 beingunrestricted to facilitate free release of processed biomass material. Areservoir of dilute sulfuric acid (or any other suitable acid) is addedto the biomass using a First Port 150, the addition occurring after afirst conveyance First Section 140 and before mixing in a mixing SecondSection 145. A reservoir of base, to be added via Second Port 155. Thebase optionally including a solid powder such as: limes stone, slakedlime, or quicklime. The base may be added after a second conveyancesection and before an additional mixing/compression section. The lengthof conveyance regions between mixing lobes 1 and 2 is such to allowbiomass to dwell for at least 10, 15 or 20 minutes at a typical Shaft135 rotation rate. Control Logic 120 configured to adapt the rotationalrate or torque of the screw extruder (Shaft 135) based on detectedcharacteristics of the biomass. These characteristics can includehardness, mass, moisture content, color, size distribution, contents,and/or any other characteristic discussed herein. To adapt operation ofProcessing System 100, Control Logic 120 typically uses outputs ofSensors 125 configured to detect these characteristics in biomass. Thecontrol logic may also adjust an amount of acid and/or base added to thebiomass while the biomass is in the screw extruder responsive to thesecharacteristics.

Several embodiments are specifically illustrated and/or describedherein. However, it will be appreciated that modifications andvariations are covered by the above teachings and within the scope ofthe appended claims without departing from the spirit and intended scopethereof. For example, Processing System 100 may further include heatingand cooling systems (active or passive), or a system for moving heatfrom hot regions to cooler regions of Extruder 110. Such systems may beused to disperse heat generated by acid-base reactions, and/or to heatbiomass in First Section 140 or prior to introduction to Extruder 110.Processing System 100 may include an active cooling (refrigeration)device and/or a circulation system configured to move heat between partsof Extruder 110. In alternative embodiments the base is added to thebiomass prior to addition of the acid, and the acid functions as theneutralizer. Add Acid Step 240 may occur using Second Port 155, beforeAdd Base Step 250.

The embodiments discussed herein are illustrative of the presentinvention. As these embodiments of the present invention are describedwith reference to illustrations, various modifications or adaptations ofthe methods and or specific structures described may become apparent tothose skilled in the art. All such modifications, adaptations, orvariations that rely upon the teachings of the present invention, andthrough which these teachings have advanced the art, are considered tobe within the spirit and scope of the present invention. Hence, thesedescriptions and drawings should not be considered in a limiting sense,as it is understood that the present invention is in no way limited toonly the embodiments illustrated.

Computing systems and/or logic referred to herein can comprise anintegrated circuit, a microprocessor, a personal computer, a server, adistributed computing system, a communication device, a network device,or the like, and various combinations of the same. A computing system orlogic may also comprise volatile and/or non-volatile memory such asrandom access memory (RAM), dynamic random access memory (DRAM), staticrandom access memory (SRAM), magnetic media, optical media, nano-media,a hard drive, a compact disk, a digital versatile disc (DVD), opticalcircuits, and/or other devices configured for storing analog or digitalinformation, such as in a database. A computer-readable medium, as usedherein, expressly excludes paper. Computer-implemented steps of themethods noted herein can comprise a set of instructions stored on acomputer-readable medium that when executed cause the computing systemto perform the steps. A computing system programmed to performparticular functions pursuant to instructions from program software is aspecial purpose computing system for performing those particularfunctions. Data that is manipulated by a special purpose computingsystem while performing those particular functions is at leastelectronically saved in buffers of the computing system, physicallychanging the special purpose computing system from one state to the nextwith each change to the stored data.

The “logic” discussed herein is explicitly defined to include hardware,firmware or software stored on a non-transient computer readable medium,or any combinations thereof. This logic may be implemented in anelectronic and/or digital device (e.g., a circuit) to produce a specialpurpose computing system. Any of the systems discussed herein optionallyinclude a microprocessor, including electronic and/or optical circuits,configured to execute any combination of the logic discussed herein. Themethods discussed herein optionally include execution of the logic bysaid microprocessor.

What is claimed is:
 1. A flow-through biomass processing systemcomprising: a screw extruder configured to convey biomass through theprocessing system such that processed biomass continuously exits theflow-through biomass processing system, the screw extruder including: ahousing configured to contain the biomass with the screw extruder, afirst shaft, a first section configured to convey the biomass throughthe screw extruder using the first shaft, a second section configured tocompress the biomass, a first port configured to introduce an acid tothe biomass, the acid being configured to promote decomposition of thebiomass, and a second port configured to introduce a base to thebiomass, the base configured to neutralize the acid, wherein the firstport is upstream of the second port. a motor configured to rotate atleast the first shaft.
 2. The system of claim 1, wherein the screwextruder is a multi-screw extruder and includes at least a second shaft.3. The system of claim 1, further comprising a third section configuredto convey the biomass through the screw extruder.
 4. The system of claim1, wherein the first port is configured to introduce the acid to thebiomass, while the biomass is within the screw extruder.
 5. The systemof claim 1, wherein the second port is configured to introduce the baseto the biomass while the base is in the screw extruder.
 6. The system ofclaim 1, wherein the screw extruder is configured to mix the base andthe biomass so as to neutralize the acid within the biomass.
 7. Thesystem of claim 1, wherein the screw extruder is configured such thatthe processed biomass that exits the flow-through biomass processingsystem is neutralized using the base.
 8. The system of claim 1, whereinthe second port is configured to add the base as a solid.
 9. The systemof claim 1, wherein the second port is configured to add a quantity ofbase to the biomass sufficient to neutralize the acid.
 10. The system ofclaim 1, further comprising a control logic configured to adapt therotational rate or torque of the screw extruder based on detectedcharacteristics of the biomass, and one or more sensors configured todetect the characteristics of the biomass.
 11. The system of claim 1,further comprising a control logic configured to add an amount of theacid to the biomass responsive to a moisture content of the biomass orresponsive to spectroscopic analysis of the biomass.
 12. The system ofclaim 1, further comprising a control logic configured to add an amountof acid to the biomass responsive to an automatically determined contentof the biomass.
 13. The system of claim 1, further comprising a controllogic configured to add an amount of the base to the biomass responsiveto an amount of the acid added to the biomass.
 14. The system of claim1, further comprising a control logic configured to add a lubricant tothe biomass in response to a rotational rate or torque of the screwextended.
 15. The system of claim 1, further comprising a control logicconfigured to add a lubricant to the biomass in response to anautomatically determined content of the biomass.
 16. A method ofprocessing biomass, the method comprising: introducing the biomass to ascrew extruder; introducing an acid to the biomass, the acid configuredto hydrolyze the biomass; introducing a base to the biomass within thescrew extruder, the base being configured to neutralize the acidintroduced to the biomass, the acid being neutralized within the screwextruder; receiving a continuous flow output of the screw extruder, theoutput including the biomass neutralized by the base.
 17. The method ofclaim 16, wherein the acid is added to the biomass while the biomass isin the screw extruder, the acid added upstream from a location withinthe screw extruder at which the base is added.
 18. The method of claim16, further comprising analyzing the biomass using one or more sensorsand using control logic to determine an amount of the acid to add to thebiomass responsive to an output of the one or more sensors.
 19. Themethod of claim 18, further comprising determining an amount of base toadd to the biomass responsive to the amount of the acid added to thebiomass.
 20. The method of claim 16, wherein the base is added to thebiomass as a solid.
 21. The method of claim 16, wherein the base and thebiomass are mixed in a section of the extruder downstream from thesecond port.